A virtual private network (VPN) extends a private network and the resources contained in the private network across public (e.g., untrusted) networks such as the Internet. For example, a VPN can enable a host computer to send and receive data across shared or public, untrusted networks by emulating the properties of the private network, such as shares, server access, and printers by establishing and maintaining certain security and management policies of the private network. This is generally implemented by establishing a virtual point-to-point connection through the use of either a dedicated connection or through a secure connection (e.g., secure network communications using various encryption techniques), or a combination of both.
A VPN connection across the Internet logically operates as a wide area network (WAN) link between the sites. A secure connection across the Internet appears to a user as a private network communication. However, this communication actually occurs over a public, untrusted network (e.g., the Internet), which is, thus, referred to as a virtual private network.